Safety is a very important design aspect of a hand grenade fuze. Conventional fuze designs account for a time delay period from initiation, for the detonation to occur, in order to ensure that the grenade is cast outside the explosion hazard area.
To this end, numerous conventional hand grenade fuzes have been proposed, some of which are described in the following publications: U.S. Pat. Nos. 3,823,669; 3,926,122; 4,063,514; 4,167,905; 4,730,559; 5,196,649; 6,082,267; 6,965,542; 7,197,983; and 7,712,419, and Statutory Invention Registration H251, issued Apr. 7, 1987 to Field.
These and other fuze designs propose the use of delay elements that are either mechanically, chemically, electrically, or electro-magnetically operated. However, these conventional designs could present various inherent problems, particularly when used in the field, under adverse and stressful conditions.
More specifically, many conventional hand grenade fuze designs include an explosive train that is always in-line from production through employment, thus presenting an intrinsic danger of inadvertent initiation.
In addition, other fuzes are designed primarily for right handed users and require different grasp and inverted handling for left-handed users, thus increasing the possibility of slippage, “milking” and functioning within close proximity.
Conventional fuze designs do not provide a visual indication (e.g., color coded) of the fuze armed and unarmed states, thus increasing the risk of inadvertently confusing the armed state for the unarmed state and creating subjective disposition of unexploded and mishandled grenades.
Certain conventional fuze designs provide for two safety features that are not required to be performed in a specific order, thus increasing the risk of unintentional functioning.
Conventional fuze designs cannot be easily returned to a safe state by the user once the safety pin is removed. As a result, once the safety pin is removed, the grenade must be deployed, regardless of the user's intent.
Many conventional fuze designs use a safety pin as a primary safety, the pin is placed through the fuze body and the ends are either shaped into a diamond, duckbill, spread, etc. Safety pin removal forces of safety pins formed concurrently in the same machinery or means for the same batch or lot may vary up to 20 pounds. As a result, the user requirements vary and are unknown until the user removes the safety and may vary from 10 pounds to 30 pounds of force required or 300% of the minimal force.
Conventional fuze designs do not necessarily provide a fail safe feature on the primary safety. The primary safety of some of these designs can be easily modified or altered by the user, or damaged by impact. Consequently, reducing the effectiveness of the primary safety and creating a risk of unintentional initiation.
The fuze primary safety design is generally tested through destructive testing, and the results are based on the sample size and the statistical analysis of results, thus the results have a high confidence level but are never 100% for the lot.
Conventional fuze designs intend for the user to have a secure grip on the lever when removing the primary safety pin but have no mechanical means to ensure this condition exists. As a result, the primary safety pin may be removed and the grenade initiated without the user having control over the grenade.
The spatial constraints on existing fuze designs pose technical risk for incorporating electronic circuitry to accomplish the detonation delay with an out-of-line explosive train. For this reason, recent fuze designs try to mechanically keep the explosive train out-of-line until the grenade is armed, thus reducing the requirement of the timing device to have a provision for such a feature.
What is therefore needed is a fuze design that addresses the following and other concerns and provides a solution thereto: effectiveness of the primary safety, out-of-line requirement, visual indication of armed state, right handed design, resafe difficulties, potential alteration or damage to the primary safety, and destructive testing. Prior to the advent of the present invention, the need for such a fuze design has heretofore remained unsatisfied.